1. Field of Invention
The invention relates to a method and an arrangement for accomplishing a function in an electronic apparatus housed within a body, which method comprises a step of drawing a virtual keyboard on a plane by means of radiation visible to the eye, a step of placing an obstacle in the keyboard pattern produced, a step of receiving radiation reflected from the obstacle, and a step of determining the position of the obstacle on the basis of the signal received. The invention further relates to a terminal employing the method as well as software means for implementing the method.
2. Brief Description of Related Developments
Various wireless devices, such as cellular phones and hand-held computers, need some kind of a physical user interface for data and command input. For example, it is known a small mobile phone keyboard with keys from 1 to 9, *, 0 and #, in addition to other possible letter characters produced by these keys. Likewise, it is known a cellular phone keyboard of a so-called xe2x80x9ccommunicatorxe2x80x9d used in cellular networks with alphanumeric keys from a to z and from 1 to 0. These keyboards are made as small as possible so that they are relatively difficult to use in comparison with keyboards of normal computers.
Touch keyboards of various sizes for electric devices are also known. Such keyboards are usually arranged in the form of a touchscreen on the device""s display. In such an arrangement, arrays of LED transmitters and receivers, for example, are placed in the frame around the screen, on more than one side of the screen. When a finger or some other obstacle is pointed at a position on the screen, a beam of infrared light is cut off, resulting in some predetermined function.
Patent application FI 990676 further discloses a method in which there is generated, by means of a plurality of infrared transceiver units, an artificial, virtual, two-dimensional keyboard arrangement on one side of an apparatus. In the close vicinity of the apparatus there is thus created a data input area, a kind of two-dimensional virtual keyboard in the X-Y plane. According to the said application, an image of the virtual keyboard can be advantageously projected on an even surface by means of a laser diode and refractive optics. The said surface on which the virtual keyboard is generated is usually the surface of a table. The exact position of an obstacle/pointer or finger on the plane determined by the virtual keyboard is detected by means of the infrared transmitters and receivers. The exact position of the obstacle on the virtual keyboard detected by the device disclosed corresponds to the execution of a certain function or to the pressing of a key on a real keyboard.
The problem with this arrangement is, however, that the received signal has a very nonlinear nature because it is reflected from an indefinite obstacle. In addition, randomly varying infrared radiation is received from the surroundings, adding to the noisiness of the received signal. Therefore, the amplitude and phase characteristics of the signal reflected/returned back to the receiver vary a great deal not just on the basis of the position of the obstacle. Thus, various tabulated correction coefficients, which have been obtained by experimentation, have to be used to calculate the position of the obstacle. Therefore, the computational processing of the received signal is difficult and requires large computing capacity in order to calculate the position of the obstacle at the desired accuracy from the received signal. In this case problems will be caused by the computing capacity of the processor and the size of the memory needed in the calculation in a cellular phone, for example. Moreover, if the position of the obstacle is to be determined in a third dimension as well (X, Y, and Z dimensions), the calculation will require very much computing capacity and memory, and to realize such a solution by conventional DSP techniques in a small handheld device is difficult.
An object of this invention is to provide a new kind of virtual keyboard which requires less computing capacity than a virtual keyboard according to the prior art.
The objects of the invention are achieved by a virtual keyboard where a keyboard pattern is drawn on a planar surface by at least one laser transmitter, and a signal potentially reflected from a finger or other obstacle is observed by at least one receiver, which signal may be interpreted as a press of a virtual key.
The method according to the invention for accomplishing a function is characterized in that the source of radiation visible to the eye for producing a virtual keyboard comprises at least one laser transmitter emitting a beam of light which both draws the desired key pattern and observes the position of an obstacle in the key pattern.
An arrangement for utilizing the method according to the invention is characterized in that the arrangement comprises a laser transmitter for drawing a virtual keyboard and observing the position of an obstacle, and a receiver for receiving radiation/light reflected from an obstacle in the virtual keyboard.
A terminal according to the invention is characterized in that the means for producing a virtual keyboard and observing an obstacle in the virtual keyboard comprises a laser transmitter and a receiver for receiving radiation/light reflected from an obstacle and a drawing control unit.
A software means according to the invention is characterized in that the software means comprises a step for determining the reception angle and reception time of a received signal, a step for verifying the validity of the reception angle, a step for verifying the validity of the reception time, a step for counting the successive reflection signals received at the different sweeps and for estimating whether a sufficient number of reflections have been received, and a step for determining that a key in the virtual keyboard has been pressed.
Advantageous embodiments of the invention are specified in the dependent claims.
The basic idea of the invention is as follows: An electronic apparatus comprises at least one laser transmitter and a receiver sensitive to light/radiation reflected from an object. A coherent beam of light from the laser transmitter is periodically deflected within an area of a desired size by means of a mirror arrangement integrated in the electronic apparatus. The movement and intensity of the laser beam are controlled so that it draws on a flat surface a virtual keyboard of a desired shape complete with figures and characters. A virtual key is considered pressed when a receiver in the electronic apparatus receives a signal reflected at a certain angle within a predetermined transit time window.
An advantage of the invention is that the drawing of the virtual keyboard and the observation of a press of a key can be realized using a single phase-coherent source of light.
Another advantage of the invention is that the virtual keyboard can be drawn using other than infrared light.
A further advantage of the invention is that the electronic apparatus requires less data processing capacity than a solution based on several transmitter-receivers operating in the infrared region.